Spectrospin Ag

Bruker Biospin Ag

Bruker Ag

Other

Werner H Tschopp

Robert Schauwecker

Pierre-Alain Bovier

Andreas Amann

Gunther R Laukien

Toni Keller

Oskar Schett

Thomas Speck

Rolf Hensel

Dieter Koch

Michael Schenkel

Martin Rindlisbacher

Phillip Hepp

Anton W Keller

Pietro Lendi

Anton Kuster

A device for compensating field disruptions in magnetic fields of electromagnets with high field homogeneity, in particular, for stabilizing the H0 field of an MR measuring system, comprising at least one field detector () for detecting interfering signals (U), at least one control loop for processing the detected interfering signals (U), and at least one compensation coil () to which the detected and processed interfering output signals (U) are transferred and which generates a correction field for compensating the interfering signals (U), is characterized in that at least one of the control loops comprises a multi-selective filter system () which comprises one or more parallel connected selective filter elements whose center frequencies can be tuned either once or in an adaptive fashion to the frequency values of the interfering signals (U) to be compensated for, wherein the outputs of these filter elements are connected to at least one of the compensation coils (). The inventive device permits selective detection of periodic field disturbances with high frequency components while a major part of the existing noise is faded out, thereby increasing the SINO.

Device and method for compensation of magnetic field disruptions in highly homogeneous magnetic fields

A matrix shim system for generating magnetic field components superimposed on a main static magnetic field, comprising a plurality of annular coils, is characterized in that it comprises g groups G. . . Gof coils, with g being a natural number &#x2267;1, wherein each group Gconsists of at least two single annular coils connected in series, wherein each group Gis designed to generate, in use, a magnetic field For each group G, there are at least two values of n for which with N: the total number of current supplies of the matrix shim system, and R: smallest inside radius of any of the annular coils of the matrix shim system. An individual, adjustable electrical current supply is provided for each group Gof coils. The inventive matrix shim system is both simple in design and stable against current fluctuations.

Matrix shim system with grouped coils

A method for operating a magnetic resonance spectrometer with a digital filter whose input is fed with an NMR signal of a time length T, and whose output signal consists of a rising oscillation Bof a length T, a signal portion [F]' which consists of a filtered FID or echo signal of the length Tand a decaying oscillation Bof a length T, wherein this output signal is initially modified using a calculation process RV, and is subsequently transformed by Fourier transformation to a desired NMR spectrum, is characterized in that, during the calculation process RV, only the signal portion [F]&#x2032; is initially selected, at least N copies of the rising oscillation Bare subsequently generated in positive time shifts Twith respect to each other and are positioned on the signal portion [F&#x2032;] in time such that the end of the first rising oscillation is positioned at the end of the signal portion, at least N copies of the decaying oscillation Bare generated in negative shifts Tand are positioned on the signal portion [F&#x2032;] in time such that the start of the first decaying oscillation is positioned at the start of the signal portion [F&#x2032;], and all N copies of the rising oscillation Bdefined in this manner and N copies of the decaying oscillation Bdefined in this manner are added to the signal portion [F&#x2032;], and only the range Tthereof which contains the signal portion [F&#x2032;] is selected as resulting signal F&#x2033; of the calculation process RV, wherein the number N is to be calculated using the formula N=T/Tand rounded to the next higher integer number. This exactly compensates for the influence of the group delay time of digital, linear-phased filters in a mathematically exact manner.

Digital filter for NMR an MRI applications

In a magnet arrangement (M, D, P , . . . , Pn) having a magnet coil system (M) with at least one current-carrying superconducting magnet coil, with an additional current-carrying coil system (D) which can be fed by an external current source to produce a magnetic field in the working volume which differs substantially from zero, and optionally with additional superconductingly closed current paths (P , . . . , Pn), wherein the magnetic fields in the z direction, generated by the additional current paths (P , . . . , Pn) due to currents induced during operation and the field of the additional current-carrying coil system (D) do not exceed 0.1 Tesla in the working volume, the additional coil system (D) is designed such that its field contribution to the working volume is determined taking into account the diamagnetism of the superconductor in the main coil system. This permits as large as possible an effective field efficiency of the additional coil system (D).

Dimensioning of magnet arrangement comprising an additional current carrying coil system

A superconducting magnet arrangement (M, S, P1, . . . , Pn) for generating a magnetic field in the direction of a z axis in a working volume, disposed about z&equals;0, comprising a magnet coil system (M) with at least one current-carrying superconducting magnet coil, a shim device (S) with at least one superconducting shim coil and additional superconductingly closed current paths (P1, . . . , Pn), wherein the magnetic fields generated in the z direction and in the working volume by the additional current paths due to induced currents during operation, do not exceed a magnitude of 0.1 Tesla, and wherein the shim device generates a field which varies along the z axis with a k power of z for an even power of k>0, is characterized in that the shim device is designed such that the effective field efficiency g of the shim device is substantially zero taking into consideration the diamagnetism of the superconductor in the magnet coil system.

Dimensioning of a superconducting shim device in a superconducting magnet arrangement

A superconducting magnet system for generating a magnetic field in the direction of a z axis in a working volume disposed about z&equals;0 with at least one current-carrying magnet coil (M) and with at least one additional, superconductingly closed current path (P , . . . , Pn), which can react inductively to the changes of the magnetic flux through the area enclosed by it, wherein the magnetic fields in the z direction in the working volume which are produced by these additional current paths during operation and due to induced currents, do not exceed a magnitude of 0.1 Tesla, is characterized in that, when an additional disturbance coil (D) produces a substantially homogeneous disturbance field in the magnet volume, the diamagnetic expulsion of the disturbance field from the main magnet coil is taken into consideration when designing the magnet coil(s) and the current paths. This permits straightforward modification of a conventionally calculated magnet arrangement to optimize the actual disturbance behavior of the system.

Dimensioning of additional current paths to optimize the disturbance behavior of a superconducting magnet system

In a temperature-control device for samples, in particular for NMR spectroscopy, comprising a vessel (20) provided with an opening (19) for receiving a measuring sample (1), an inlet opening (10) for introduction of the fluid, an outlet opening (15) for the outflow of the fluid and a flow channel (18) through which at least a partial flow of the fluid is guided past the sample (1), as direct fluid flow, from the bottom to the top, there is provided at least one by-pass channel (17) which is arranged in such a way that an additional partial fluid flow can be guided past the upper area of the said sample (1) in the form of a by-pass fluid flow (7). This enables also the upper area of the sample (1) to be temperature-controlled in an efficient way so as to minimize the temperature gradient in the sample (1). The temperature-control device may comprise, in the upper area of the sample (1), a heat-exchanger system (14) which concentrates the direct fluid flow ( 8), after it has been combined with the by-pass fluid flow (8), around the sample (1). One achieves in this manner efficient temperature control of the upper section of the sample by the fluid flow, without any disturbing thermal obstacles.

Temperature-control device for samples

An apparatus is employed to compensate for time-variant field interference in magnetic fields of electromagnets with high field homogeneity, in particular in specimen areas of superconductive electromagnets for measurements of magnetic resonance. The magnetic field that permeates a specimen area of the electromagnet is identified by means of at least one induction coil, a voltage induced in the induction coil is supplied to a control stage, and a compensating current that flows through a compensating coil that surrounds the specimen area is set by means of an output signal from the control stage. In order to be able to compensate for remote interference emanating from far outside the magnet, at least one compensating coil and at least two induction coils, or vice versa, are disposed. Disposed in the control stage is either a voltage adder, to which the induced currents of the at least two induction coils can be supplied and differently weighted, or a current divider, which supplies differently weighted compensating currents to at least two compensating coils. The induction voltages or compensating currents can be weighted as a function of frequency.

Apparatus for compensating for time-vibrant field interference in

A method and apparatus are proposed for homogenizing the field of a primary magnetic coil which can be energized from a primary current source and operated in a superconductive manner and short-circuited by means of superconducting switches. A profile of the uncorrected field of the primary coil is measured along an axis of the coil, and parameters for compensating fields are determined from the profile, with the compensating fields then being superimposed on the uncorrected field. In order to avoid the necessity of having to re-heat and then cool the primary coil for attachment of correcting windings for the compensating fields, the invention calls for separately energizable supplementary coils to be brought to a low temperature together with the primary coil, the field profile of the primary coil to be measured, the corresponding field gradients to be determined therefrom, and correcting currents for each individual supplementary coil to be determined therefrom and set, with the superconducting switches of the supplementary coils then being made.

Method for homogenizing the field of a magnetic coil and apparatus

The invention relates to a spin resonance spectrometer comprising a sample vessel 3 for receiving a substance to be investigated, a driving device having a rotor 31 in which the sample vessel is located, and at least one pipe 45 for the supply and discharge of test substances and if necessary rinsing media. The pipe 45 projects into the sample vessel 3 coaxially with respect to its axis of rotation. The sample vessel 3 is open at both its ends and the pipe 45 is connected to one end by a fluid tight low friction bearing 43.

Spin resonance spectrometer

A spin resonance spectrometer having a sample vessel 83 for containing substances to be examined. Pipes 92, 93 for the supply and discharge of test substances and possibly rinsing media are connected to the sample vessel, the pipe serving for supplying substances being connected to the sample vessel 83 such that the direction of movement of the substance supplied, on entering the sample vessel 83, has a component directed tangentially with respect to the sample vessel. As a result the supplied substance rotates in the sample vessel. The supply pipe 92, 93 may open substantially tangentially into the sample vessel 83, or a connecting member 184 comprising at least approximately helical channels may be located between the pipe 192 and the sample vessel 183.

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Aesch/Forch, Switzerland

Werner H Tschopp